Speedometer Module: Description and Operation
PURPOSEThe Programmable Speedometer/Odometer Module (PSOM) receives a speed signal input from the Differential Speed Sensor (DSS) and uses a programmed conversion constant to convert the signal to the standard 8000 pulses-per-mile speed signal output.
In the vehicle, the PSOM and Rear Anti-lock Brake Module are parallel users of the DSS signal. The speed signal output is proportional to the road speed of the vehicle. The Programmable Speedometer/Odometer Module supplies this signal to the Speed Control Amplifier, the Instrument Cluster (Electronic), and the Powertrain Control Module (PCM), all of which require vehicle speed information.